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ENGINEERING   continued


      Convertible tops were also redesigned this year to give the cars more of a hardtop look. Sealing at the top of the windshield is tighter, resulting in a minimum of wind noise. Top side locks now allow larger levers for easier operating with less effort.
      One of the most valuable new accessories on this year's Pontiac is the new automatic temperature control for the air-conditioning system. This now gives a sensor-controlled interior temperature, regardless of the outside or engine temperatures. You merely set the desired interior comfort level on a dial in the air-conditioning control panel.
      Automatic temperature control is helpful in summer and winter. In warm weather, it'll cool the car to any pre-set level. At temperatures over 35 F., the system removes excess moisture from the air. Thus it increases passenger comfort in humid weather plus limiting window fogging and inside condensation.
      Before we finished our design, we talked to over 200 Cadillac dealers to find out about their experience with Cadillac's similar system. As a result, we made further improvements of our own. One of the more important of these was our sun-load compensation. This handles the situation often found in the mountains, where the sun is often quite hot, but the air's cold.
      The interior of the '65 Pontiac has quite a few other improvements that increase convenience, appearance, and safety. For example, there are new sun visors that fit more tightly against the headliner. Our new instrument panel features a luxurious, leather-grained texture highlighted by chrome cast in the panel. Three instrument "bomb" openings are located in the center of the panel, and there's a reinforcement panel running full width. Within easy reach of all passengers, there's a new, twin-chambered ashtray that slides on ball bearings. This makes opening and closing it easier and less damaging to fingernails. The ashtray also has an improved positive release tab for quicker cleaning. Our new fuel gauge has several times as much power as before and therefore is less subject to dirt in critical points or to weather variations.
      The turn-signal mechanism is the same, except that this year its flasher is mounted on the instrument panel reinforcement rather than on the firewall. Surprisingly, this makes it quite a bit louder. It's particularly helpful to older people. This year's horn is actuated by bars in the two steering wheel spokes. Besides being more contemporary, the new design allows a little better view of the instrument panel.
      The standard steering wheel has been newly designed and has a shallow rim-to-hub depth. The wheel hub is smaller in diameter for a better look. Also, the diameter of the steering column has been reduced from 23/8 inches to two inches, also for better appearance. An improved steering column attachment unit makes for a more solid mounting.
      We've kept our exclusive self-adjusting manual steering gear on both the Pontiac and Tempest. Rack-and-pinion steering gears sometimes get loose and noisy after some usage. To compensate for this, we install a spring between the worm adjuster nut and the lower bearing to maintain bearing adjustment, thus eliminating click and clatter for the life of the car.
      We've made a number of changes in our drive train. Starting at the front, cross-flow radiators on all '65 Pontiacs offer improved cooling, at the same time making possible a lower front-end silhouette. Because the low, wide shape of this radiator matches the grille opening better, it's possible to have greater radiator exposure and more effective cooling surface. This radiator offers other advantages. De-aeration is better than on a down-flow radiator. This refers to the ability of a radiator to get rid of air bubbles trapped in the coolant. Air, being a less effective heat conductor than water, interferes with proper cooling.
      Interestingly, some of our competitors have been using cross-flow radiators for several years, but they abandoned them this year, partly because of the expense of having a separate surge tank to keep the necessary low profile. But a young man at the Harrison Division figured out how the separate surge tank could be eliminated. This makes the cross-flow radiator economically logical. All GM B-bodies have this radiator, but ours is a little different from the others.
      The 1965 Pontiac engines can boast more smoothness, better fuel economy, higher horsepower, and lower weight. All this produces better performance and durability. Improved engine breathing comes by way of new intake manifolds that distribute the fuel/air mixture more efficiently by larger intake and exhaust passages in the cylinder heads, and by larger intake and exhaust valves. As a result, the engine engineers have been able to recalibrate the carburetors on the lean side, thereby improving performance and fuel economy.
      The all-new, optional Turbo Hydra-Matic automatic transmission offers increased performance, plus smoother, quicker, more responsive shifting. This transmission consists primarily of a three-element hydraulic torque converter and a compound planetary gearset.
      The high starting ratio of this transmission (more than 5 to 1, compared with about 3 to 1 in the Roto Hydra-Matic) has let us lower the axle ratio to a record 2.41 to 1 on some models. Improved fuel economy will be quite noticeable. With this axle, we're continuing with the lowest ratio in the industry. We firmly believe that a low axle ratio and a powerful engine make the best car. For one thing, the engine runs more slowly at any given speed. The only factor you lose with this ratio is a slight amount of highway passing performance. But we get this back with our throttle downshift, which keeps the transmission in second until you've passed safely and back off the gas pedal.
 

Bevy of engineers in chassis department work hard to draft details of Pontiac frames and running gear for future models.

 

 

A new process of sealing both windshield and back glass of all Pontiacs is made by Thiokol, shown being applied through hose.

 

MOTOR TREND
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February, 1965

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